The present invention relates to an assembling or a processing system capable of assembling or processing various mechanical parts of a large variety of weight making use of a single industrial robot.
In recent years, there is an increasing demand for automation of large lot and small quantity production process, particularly in the assembling process for assembling various mechanical parts of a large variety of shape and weight. For automation of such an assembling process, hitherto, it has been necessary to employ specific assembling machine having a single function for each kind of parts to be assembled. In consequence, the whole assembling process requires a large number of assembling machines of different kinds to occupy an impractically large installation space. In addition, the rate of operation of each assembling machine is lowered impractically. Furthermore, the conventional automatic assembling system has small flexibility or adaptability to any change of the assembling procedure due to a change of the parts to be assembled or the like reason.
Under this circumstance, various attempts have been made to develop an assembling system incorporating an industrial robot, having a wide adaptability to a large variety of jobs and a high flexibility to cope with changes of the procedure. However, in the case where the parts to be assembled together has a wide variety of weights from several tens of grams to hundred kilograms or more for example, it is extremely difficult to conduct all tasks by a single robot, because of limitation in the specification of the robot. In such a case, therefore, it has been necessary to use a plurality of industrial robots such as an industrial robot for small weight and size and another industrial robot for large size and weight, so that each robot can handle the parts of weights meeting its specification.
In the assembling equipment incorporating a plurality of industrial robots, however, an uneconomically large installatoin space is required for installation of these robots. In addition, the rate of operation of each robot is impractically low.
For instance, a conventional system shown in FIG. 1, (which is disclosed in Japanese Patent Laid-Open No. 6271/1979) has a heavy duty robot A which is simple, less expensive and capable of handling heavy loads, and an indexing robot B adapted for indexing the wrist of the heavy duty robot A in the directions of X and Y axes. These robots A and B are connected to each other by a telescopic means 7. More specifically, the indexing robot (sub-robot) B includes a guiding device 10 adapted for horizontally guiding a holding portion 8 of the heavy duty robot (main robot) A which can move only in the direction of Z axis in accordance with an instruction given by a controller 1, and a driving controller 11 for controlling the horizontal running of the holding portion 8. In this system, the vertical movement of the holding portion 8 is achieved by the main robot, while the horizontal movement is effected by the sub-robot, so that the precise control of the transfer or convey of the object to the designated point is conducted by a system having a simple construction.
The guiding device 10 of the sub-robot B is constituted by four pillars 12 to 15 arranged in a parallelopiped form, four guide rails 16 to 19 carried by the pillars 12 to 15, and a running rail 20 adapted to linearly run along the parallel guide rails 16, 18. Running blocks 21, 22 adapted to run along the guide rails 16, 18 are secured to both ends of the running rail 20. The driving controller 11 of the sub-robot B includes a driving block 23 adapted to run linearly along the running rail 20, telescopic means 7 fixed to the lower face of the driving block 23 and to the holding portion 8 of the main robot A so as to mechanically connect the main robot A and the sub-robot B, driving device mounted in the driving block 23 and adapted to drive the latter, and driving devices mounted in the running blocks 21, 22 and adapted to drive these running blocks.
The driving controller 11 of the sub-robot is designed and arranged to permit the transportation of loads such as parts to any point within a predetermined area corresponding to the object of the task to be performed by the robot. In the system having the described construction, the vertical movement of the holding portion 8 achieved by actuating the driving box 1 of the main robot A in accordance with an instruction delivered by the control box. Therefore, the telescopic means 7 secured to the holding portion 8 caused by the main robot A. On the other hand, the horizontal movement of the holding portion 8 is achieved by linearly driving the running blocks 21, 22 and the driving block 23 along the guide rails 16, 18 and the running rail 20, respectively, by giving position data in X and Y axis directions to the driving controller 11 from the control box. Namely, as the driving block 23 is positively driven in the X and Y axis directions linearly, the holding portion 8 integrally attached to the driving block 23 is mvoed in the same direction in a passive manner. The horizontal movement of the holding portion 8 is thus performed.
In the assembling or processing system of the type described, the transportation of the load, i.e. parts, is divided into two separate tasks, i.e. the vertical movement and the horizontal movement, which are shared by different robots, i.e. the main robot and the sub-robot, operatively connected to each other, to transport the load precisely to the designated position.
In this system, however, the sub-robot B is an imperfect robot and cannot assemble or process light-weight articles by itself independently of the operation of the main robot. For this reason, the described system cannot have a sufficiently high flexibility to fail to deal with a large variety of tasks.